Absorption refrigeration apparatus of the inert gas type



June 2, 1970 w. G. KOGEL ABSORPTION REFRIGERATION APPARATUS OF THEINER'I' GAS TYPE Filed Sept. 25, 1968 l INVENIIFOR. BY fixwnw Z; ATTORNEY Patented June 2, 1970 3,514,972 ABSORPTION REFRIGERATIONAPPARATUS OF THE INERT GAS TYPE Wilhelm Georg Kiigel, Stockholm, Sweden,assignor to Aktiebolaget Electrolux, Stockholm, Sweden, a corporation ofSweden Filed Sept. 25, 1968, Ser. No. 762,426 Claims priority,application Sweden, Sept. 29, 1967, 13,436/ 67 Int. Cl. F25b 15/10 U.S.Cl. 62-490 8 Claims ABSTRACT OF THE DISCLOSURE Absorption refrigerationapparatus of the inert gas type in which refrigerant vapor is expelledfrom solution at a place of heating and condensed at a place ofcondensation, a circuit for circulating inert gas which includes anabsorber and evaporator structure having a plurality of evaporatorsections respectively operable at low and higher temperatures, thecircuit having a Weak gas line for flowing inert gas weak in refrigerantfrom the absorber to the low temperature evaporator section and a richgas line for flowing inert gas enriched in refrigerant from theevaporator structure to the absorber, conducting liquid refrigerant fromthe condenser to the evaporator structure in a path of flow whichincludes a precooler, conducting inert gas in the inert gas ci-rcuit tothe precooler and conducting inert gas, after flowing in physicalcontact with liquid refrigerant in the precooler, to a zone of theevaporator structure at which the inert gas is at least partiallyenriched in refrigerant.

BACKGROUND OF THE INVENTION Field of the invention In absorptionrefrigeration apparatus of the inert gas type it has been the practiceheretofore to precool liquid refrigerant in its path of flow from acondenser to an evaporator structure by flowing inert gas enriched inrefrigerant into the presence of the liquid refrigerant before thelatter is introduced into the evaporator structure which may include afirst evaporator section operable at a low temperature for freezingpurposes and a second evaporator section operable at a highertemperature to promote storing of food and the like at a refrigeratingtemperature above the freezing temperature.

Description of the prior art It has been proposed heretofore to positionabove an evaporator structure a gas heat exchanger which is connected inthe inert gas circuit and through which inert gas rich in refrigerantvapor flows in heat exchange relation with inert gas weak in refrigerantvapor. Inert gas enriched in refrigerant in the evaporator structureflows through the gas heat exchanger into the presence of liquidrefrigerant flowing from the condenser to the evaporator structure.Liquid refrigerant in the gas heat exchanger evaporates and takes upheat from liquid refrigerant and also from enriched inert gas. Further,heat exchange is effected between weak and enriched gas in the gas heatexchanger, thereby cooling the weak inert gas. In this way liquidrefrigerant and weak inert gas flowing to the evaporator structure areintroduced therein at a lower temperature than a temperature when noprecooling of these fluids is effected.

Since the gas heat exchanger in its entirety is employed to promoteprecooling of liquid refrigerant, the function of the gas heat exchangerto effect optimum heat exchange between weak and rich inert gas isimpaired. This is so because the weak inert gas flowing to theevaporator structure is not effectively cooled in the gas heat exchangerby its heat interchange with rich inert gas and hence it is introucedinto the evaporator structure at a higher temperature than otherwisewould result if the gas heat exchanger could function as originallyintended.

Moreover, the rich inert gas cooled by evaporation of liquid refrigerantin the gas heat exchanger flows from the latter at a relatively lowtemperature without being eflfectively employed to produce refrigerationin the evaporator structure to produce the lowest possible refrigeratingtemperature, which is objectionable. This is especially true inrefrigerators having several thermally segregated compartments in one ofwhich freezing temperatures must be maintained by one evaporator sectionand satisfactory temperatures must be maintained by another evaporatorsection to preserve foods and the like at refrigerating temperaturesabove the freezing temperature.

It also has been proposed to flow weak inert gas from the gas heatexchanger into the presence of liquid refrigerant in a precoolerprovided in the path of flow of liquid refrigerant from the condenser tothe evaporator structure, and, after effecting precooling of liquidrefrigerant, flowing the partially enriched inert gas from the precoolerto the absorber in the system. However, such a proposal results in lossof useful refrigerating effect. With this arrangement it is necessary toprovide two parallel paths of flow for enriched inert gas, one from theprecooler to the absorber and the other from the evaporator structure tothe absorber. This is objectionable because it is diflicult to controlflow of inert gas in parallel paths of flow in the inert gas circuit,especially when disturbances can often occur due to changes andvariations in conditions encountered during operation of therefrigeration system.

SUMMARY OF THE INVENTION My invention relates to absorbtionrefrigeration apparatus of the inert gas type adapted to producerefrigeration at a plurality of temperatures, and it is an object toeffect a lower refrigeration temperature in the low temperature sectionof a plural temperature evaporator structure.

In accord with the invention, a substantial cooling output is effectedat an extremely low temperature level without jeopardizing the totalcooling output of the refrigeration system. I accomplish this byeffecting thelower temperature level in such manner that inert gas inthe insert gas circuit flows to a precooler into the presence of liquidrefrigerant in its path of flow from a condenser to the evaporatorstructure. The inert gas, after flowing in physical contact with liquidrefrigerant in the precooler, flows to a zone of the evaporatorstructure at which the inert gas is at least partially enriched inrefrigerant.

The zone of the evaporator structure to which inert gas is conducted maybe at the region thereof at which the gas outlet of the first evaporatorsection is connected to the gas inlet of the second evaporator section.

. The low and higher temperature evaporator sections respectively arearranged to abstract heat from thermally segregated compartments of aninsulated refrigerator cabinet, the low temperature evaporator sectionfunctioning to maintain freezing temperatures in one compartment and thehigher temperature evaporator section functioning to maintainrefrigerating temperatures above the freezing temperature in anothercompartment.

BRIEF DESCRIPTION OF THE DRAWING In the drawing, the single figure moreor less diagrammatically illustrates an absorption refrigerationapparatus of the inert gas type embodying my invention.

3 DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing, Ihave shown my invention in connection with a refrigerator having athermally insulated space which is divided by a partition 11 into aplurality of compartments 12 and 14 one above the other and arranged tobe cooled by evaporator structure comprising first and second evaporatorsections 15 and 16 operable at different temperatures. The evaporatorsections 15 and 16 are arranged to abstract heat from the interior ofthe refrigerator 10', the upper compartment 12 being cooled primarily bythe evaporator section 15 so as to freeze water and other matter as wellas store frozen food packages therein.

The partition 11 functions to prevent circulation of air between theupper and lower compartments 12 and 14 and thermally shields theevaporator sections 15 and 16 from one another. Hence, the upper andlower compartments 12 and 14 are thermally segregated from one another.

The first evaporator section 15, which may be in the form of ahorizontally disposed looped coil, is provided with a suitable heatdissipating surface, such as the plurality of heat transfer members 15a,for example. The second evaporator section 16 also may have a suitableheat dissipating surface formed from a plurality of heat dissipatingmembers 16a, for example. The lower refrigerating compartment 14, whichmay serve as a space in which food and the like is stored at atemperature above the freezing temperature, is cooled primarily by theevaporator section 16.

The evapoartor sections 15 and 16 constitute the evaporator structure ofabsorption refrigeration apparatus of the inert gas type and areconnected by conduits to other parts of the apparatus for circulation ofinert gas as well as supply liquid refrigerant to the evaporatorstructure. In apparatus of this type, refrigerant expelled from asolution in a generator 17 by heating passes upward through an aircooled rectifier 18 into an air cooled condenser 19 in which theexpelled refrigerant is condensed and liquefied. Liquid refrigerantflows from condenser 19 through a precooler 20 in which precooling ofliquid refrigerant is effected, as will be described presently, andrefrigerant flows therefrom through a conduit 21 into the evaporatorsections 15 and 16.

In evaporator sections 15 and 16 the refrigerant evaporates and diffusesinto an inert gas, such as hydrogen, for example, to produce arefrigerating effect and abstract heat from the surroundings. Theresulting gas mixture of refrigerant and inert gas flows from evaporatorsections 15 and 16 through a conduit 22 and an outer passageway 23 of agas heat exchanger 24 and a conduit 25 into an absorber comprising avessel 26 and a looped coil 27. -In the absorber vessel 26 and loopedcoil 27 refrigerant vapor is absorbed into a liquid absorbent, such aswater, for example, which enters through a conduit 28. The hydrogen orinert gas, which is practically insoluble and weak in refrigerant, isreturned to evaporator sections 15 and 16 through a conduit 29 and innerpassageway 30 of the gas heat exchanger 24.

Absorption liquid enriched in refrigerant in the absorber flows fromvessel 26 through a conduit 31 to generator 17 where it is heated andrefrigerant vapor again is expelled out of solution. The weakenedabsorption liquid from which liquid has been expelled flows fromgenerator 17 through a conduit 32 and conduit 28 to coil 27 to absorbrefrigerant vapor again, the conduit 32 desirably being in heat exchangerelation with conduit 31.

The gas heat exchanger 24 comprises outer and inner conduits 33 and 34which form the outer and inner passageways 23 and 30, respectively, ofthe heat exchanger. The conduit 29 for conducting weak inert gas fromthe upper end of absorber coil 27 to the gas heat exchanger 24 extendsdownward from the upper end of the coil to a region 35 at the lower endof the gas heat exchanger 24 which is near the absorber vessel 26. Thelower end of conduit 29, at the region 35, is connected to the lower endof the conduit 34 which forms the inner passageway 30 of the gas heatexchanger 24. At the region 35 the conduit 34 includes a downwardextending portion 34a which extends below the liquid surface level 26aof the body 26b of absorption liquid in the absorber vessel 26. Theconduit 25 through which inert gas enriched in refrigerant flows intothe absorber vessel 26, on the other hand, discharges the rich gasmixture into the absorber vessel 26 into the vapor space therein abovethe liquid surface level 26a.

In accordance with my invention, in order to introduce liquidrefrigerant to the first evaporator section 15 at a lower temperaturethan the temperature at which it flows from the condenser 19, therefrigerant is cooled in the precooler 20 by flowing thereto inert gasin the inert gas circuit. Weak inert gas flowing from the upper end ofthe inner passage 30 of the horizontal portion of the gas heat exchanger24 flows into the conduit 21 in its path of flow to the evaporatorsection 15. In the conduit 21, at the region 36 thereof, a portion ofthe weak inert gas is diverted into the lower end of conduit 20. Thediverted weak gas flows upward in the precooler 20, as indicated by thearrow A, such upward flow of Weak inert gas being countercurrent todownward flow of liquid refrigerant. Liquid refrigerant in the precooler20 evaporates and diffuses into the weak inert gas and takes up heatfrom liquid refrigerant flowing to the evaporator section 15 throughconduit 21.

The weak gas, which becomes partially enriched in refrigerant vapor inthe precooler 20, flows downward from the upper part thereof through aconduit 37, as indicated by the arrows B, to a zone 38 of the evaporatorstructure at which the inert gas is at least partially enriched inrefrigerant. The zone 38 of the evaporator structure is at a conduit 39which connects the gas outlet end of the first evaporator section 15 andthe gas inlet end of the second evaporator section 16.

Since inert gas weak in refrigerant vapor initially flows through thefirst evaporator section 15 and partially enriched gas then flowsthrough the second evaporator section 16, the inert gas in theevaporator section 15 contains a lesser amount of regrigerant vapor thanthe inert gas in the evaporator section 16. The partial vapor pressureof the refrigerant is a gradient, so that the temperature in theevaporator section 15 and 16 also is a gradient, the evaporatingtemperature of liquid refrigerant being lower in evaporator section 15which constitutes the freezing portion of the evaporator structure.

An important aspect of the invention is that diverted weak inert gas,which is capable of producing a low temperature refrigerating elfect, iseffectively employed in the precooler 20 to reduce the temperature ofthe liquid refrigerant flowing to the evaporator section 15; and suchdiverted gas thereafter is employed in the evaporator section 16 toproduce a sufliciently low temperature in the compartment 14 in whichfoods and the like are maintained at a refrigerating temperature abovefreezing temperature. The inert gas flowing through the conduit 37desirably enters the zone 38 of the evaporator structure at the samepartial pressure of refrigerant vapor as that of the inert gas reachingthe zone 38 at the gas outlet of the first evaporator section 15.

In view of the foregoing, it will now be undestood that the conduit 34of the gas heat exchanger 24, which forms the inner passageway 30 andmay be referred to as a weak gas line, extends from the region 35adjacent to the absorber vessel 26 to the region 40 at which the conduit21 is connected thereto. The outer conduit 33 of the gas heat exchanger,which envelops the inner conduit 34 to pro vide the outer passageway 23and may be referred to as a rich gas line, extends to the absorbervessel 26 from the region 41 at which the conduit 22 is connectedthereto. The lower end of the precooler 20 is connected to the weak gasline at the region 36 thereof which is before inert gas reaches the gasinlet of the first evaporator section 15 and after heat interchange hasbeen effected between Weak gas and rich gas in the gas heat exchanger24.

Inert gas partially enriched in refrigerant in the first evaporatorsection 15 flows from the gas outlet end thereof through the conduit 39to the gas inlet end of the second evaporator section 16. Unevaporatedliquid refrigerant also flows from the first evaporator section 15through the conduit 39 into the second evaporator section 16. Inert gasenriched in refrigerant flows from the gas outlet end of the secondevaporator section 16 through conduit 22 to the region 41 of the outerpassageway 23 of the gas heat exchanger 24, and unevaporated refrigerantflows from the lower end of the second evaporator section 16 through aconduit 42 to the outer passageway 23 of the gas heat exchanger. Theconduit 42 is formed to pro- Vide a liquid trap and is connected at theregion 43 to the gas heat exchanger 24.

I claim:

1. In a refrigerator,

(a) a cabinet comprising thermally insulated walls defining an insulatedinterior having a plurality of spaces thermally segregated from oneanother, one of said spaces functioning as a freezing compartment andthe other of said spaces functioning as a compartment for refrigeratingfoods at a temperature above freezing temperature,

(b) absorption refrigeration apparatus of the inert gas type comprisingavapor expulsion unit for expelling refrigerant vapor from solution,

() refrigerant liquefying means in which liquefaction of expelled vaporis effected,

(d) a gas circuit including an absorber having an inlet for inert gasenriched in refrigerant vapor and an outlet for inert gas weak inrefrigerant vapor and evaporator structure including first and secondevaporator sections each respectively having an inlet and outlet forinert gas,

(e) said first evaporator section being arranged to abstract heat fromthe freezing compartment and said second evaporator section beingarranged to extract heat from the food storage compartment,

(f) said gas circuit including a weak gas line for fiowing inert gasweak in refrigerant vapor from the outlet of said absorber to the inletof said first evaporator section and a rich gas line for flowing inertgas enriched in refrigerant vapor from said evaporator structure to theinlet of said absorber,

(g) first conduit means including a precooler for flowing liquidrefrigerant from said refrigerant liquefying means to said evaporatorstructure,

(h) means connecting said precooler in said inert gas circuit forflowing inert gas thereto in the presence of liquid refrigerant, and

(i) second conduit means for conducting inert gas, after flowing inphysical contact with liquid refrigerant in said precooler, to a zone ofsaid evaporator structure at which the inert gas is at least partiallyenriched in refrigerant.

2. Apparatus as set forth in claim 1 which includes third conduit meansconnecting the gas outlet of said first evaporator section and the gasinlet of said second evaporator section, said zone of said evaporatorstructure to which inert gas is conducted from said precooler by saidsecond conduit means comprising said third conduit means.

3. Apparatus as set forth in claim 1 which includes a gas heat exchangerhaving first and second passageways, said first passageway forming apart of said weak gas line and said second passageway forming a part ofsaid rich gas line, and said connecting means for flowing inert gas tosaid precooler communicating with said weak gas line at a region thereofwhich is before inert gas reaches the gas inlet of said first evaporatorsection and after heat interchange has been effected between weak gasand rich gas in said gas heat exchanger.

4. Apparatus as set forth in claim 1 in which the partial pressure ofrefrigerant vapor of the inert gas reaching said zone in said evaporatorstructure is substantially the same as that of the inert gas flowing tosaid zone through said second conduit means.

5. Absorption refrigeration apparatus of the inert gas type comprising(a) a vapor expulsion unit for expelling refrigerant vapor fromsolution,

(b) refrigerant liquefying means in which liquefaction of expelled vaporis effected,

(c) a gas circuit including an absorber having an inlet for inert gasenriched in refrigerant vapor and an outlet for inert gas weak inrefrigerant vapor and evaporator structure including first and secondevaporator sections each respectively having an inlet and outlet forinert gas,

(d) said first evaporator section being operable at one temperature andsaid second evaporator section being operable at a higher temperature,

(e) said gas circuit including a weak gas line for flowing inert gasweak in refrigerant vapor from the outlet of said absorber to the inletof said first evaporator section and a rich gas line for flowing inertgas enriched in refrigerant vapor from said evaporator structure to theinlet of said absorber,

(f) first conduit means including a precooler for flowing liquidrefrigerant from said refrigerant liquefying means to said evaporatorstructure,

(g) means connecting said precooler in said inert gas circuit forflowing inert gas thereto in the presence of liquid refrigerant, and

(h) second conduit means for conducting inert gas after flowing inphysical contact with liquid refrigerant in said precooler, to a zone ofsaid evaporator structure at which the inert gas is at least partiallyenriched in refrigerant.

6. Apparatus as set forth in claim 5 which includes third conduit meansconnecting the gas outlet of said first evaporator section and the gasinlet of said second evaporator section, said zone of said evaportorstructure to which inert gas is conducted from said precooler by saidsecond conduit means comprising said third conduit means.

7. Apparatus as set forth in claim 6 which includes a gas heat exchangerhaving first and second passageways, said first passageway forming apart of said weak gas line and said second passageway forming a part ofsaid rich gas line, and said connecting means for flowing inert gas tosaid precooler communicating with said weak gas line at a region thereofwhich is before inert gas reaches the gas inlet of said first evaporatorsection and after heat interchange has been effected between weak gasand rich gas in said gas heat exchanger.

8. Apparatus as set forth in claim 7 in which the partial pressure ofrefrigerant vapor of the inert gas reaching said zone in said evaporatorstructure is substantially the same as that of the inert gas flowing tosaid zone through said second conduit means.

References Cited UNITED STATES PATENTS 3,177,675 4/1965 Kogel 62490 XLLOYD L. KING, Primary Examiner US. Cl. X.R. 62492

